Block copolymers and method for making same

ABSTRACT

The present invention is a novel block copolymer containing a controlled distribution copolymer block of a conjugated diene and a mono alkenyl arene, where the controlled distribution copolymer block has terminal regions that are rich in conjugated diene units and a center region that is rich in mono alkenyl arene units. Also disclosed is a method for manufacture of the block copolymer.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application is a divisional of U.S. patent application Ser.No. 10/359,981, filed Feb. 6, 2003, entitled Novel Block Copolymers andMethod for Making Same.

The present application is related to commonly assigned U.S. patentapplication Ser. No. 10/359,906 entitled Polymer Modified BitumenCompositions, now U.S. Pat. No. 6,759,454, commonly assigned U.S. patentapplication Ser. No. 10/359,907 entitled Articles Prepared FromHydrogenated Controlled Distribution Block Copolymers, now published asUS2003/0181585 A1, commonly assigned U.S. patent application Ser. No.10/359,927 entitled Adhesives and Sealants From Controlled DistributionBlock Copolymers, now published as US2003/0176574 A1, commonly assignedU.S. patent application Ser. No. 10/359,953 entitled Articles PreparedFrom Controlled Distribution Block Copolymers, now published asUS2003/0166776 A1, commonly assigned U.S. patent application Ser. No.10/359,462 entitled Gels From Controlled Distribution Block Copolymers,now published as US2003/0153681 A1, all of which were filed Feb. 6, 2003and commonly assigned International Patent Application Ser. No.PCT/NL03/00098 filed on Feb. 7, 2003 entitled Solvent-Free, Hot MeltAdhesive Composition Comprising a Controlled Distribution BlockCopolymer, now published as WO 03/066769 A1, and commonly assigned U.S.patent application Ser. No. 10/209,285 filed Jul. 31, 2002 entitledElastomeric Articles Prepared From Controlled Distribution BlockCopolymers, now published as US2003/0181584 A1, all of which claimpriority from U.S. Provisional Patent Application Ser. No. 60/355,210filed Feb. 7, 2002.

FIELD OF THE INVENTION

This invention relates to novel anionic block copolymers of mono alkenylarenes and conjugated dienes, and to the methods for making such blockcopolymers. In particular, the invention relates to anionic blockcopolymers where one of the blocks is a controlled distributioncopolymer of a conjugated diene and mono alkenyl arene having a specificarrangement of the monomers in the copolymer block.

BACKGROUND OF THE INVENTION

The preparation of block copolymers is well known. In a representativesynthetic method, an initiator compound is used to start thepolymerization of one monomer. The reaction is allowed to proceed untilall of the monomer is consumed, resulting in a living homopolymer. Tothis living homopolymer is added a second monomer that is chemicallydifferent from the first. The living end of the first polymer serves asthe site for continued polymerization, thereby incorporating the secondmonomer as a distinct block into the linear polymer. The block copolymerso grown is living until terminated.

Termination converts the living end of the block copolymer into anon-propagating species, thereby rendering the polymer non-reactivetoward monomer or coupling agent. A polymer so terminated is commonlyreferred to as a diblock copolymer. If the polymer is not terminated theliving block copolymers can be reacted with additional monomer to form asequential linear block copolymer. Alternatively the living blockcopolymer can be contacted with multifunctional agents commonly referredto as coupling agents. Coupling two of the living ends together resultsin a linear triblock copolymer having twice the molecular weight of thestarting, living, diblock copolymer. Coupling more than two of theliving diblock copolymer regions results in a radial block copolymerarchitecture having at least three arms.

One of the first patents on linear ABA block copolymers made withstyrene and butadiene is U.S. Pat. No. 3,149,182. These polymers in turncould be hydrogenated to form more stable block copolymers, such asthose described in U.S. Pat. Nos. 3,595,942 and Re. 27,145. In somecases what was desired was a random copolymer, such as an SBR, ratherthan a block copolymer. Random styrene butadiene copolymers or SBR aredisclosed in U.S. Pat. Nos. 2,975,160, 4,547,560, 4,367,325 and5,336,737.

Inventors desiring a low melt viscosity in block copolymers consideredthe use of random styrene and butadiene blocks, as disclosed in U.S.Pat. No. 3,700,633. One means of introducing transparency to blockcopolymers was to also provide for random blocks, such as in U.S. Pat.Nos. 4,089,913, 4,122,134 and 4,267,284.

When preparing random blocks of styrene and butadiene, so-called“tapered” blocks would result due to the fact that butadienecopolymerizes at a faster rate than does styrene. See, e.g. U.S. Pat.Nos. 5,191,024, 5,306,779 and 5,346,964. So in U.S. Pat. No. 4,603,155the patentee prepared a block comprising multiple tapered blocks toachieve a more random copolymer. But in many cases the patentee relieson the continuous addition of both monomers or the use of randomizingagents to achieve a more random structure. Such techniques are disclosedin U.S. Pat. Nos. 3,700,633 and 4,412,087 and German patent applicationsDE 4420952, DE 19615533, DE 19621688, DE 195003944, DE 19523585, and DE19638254. However, some randomizing agents will poison hydrogenationcatalysts, and make the subsequent hydrogenation of the polymersdifficult or impossible, so such randomizing agents must be avoided.Randomization agents containing N atoms are particularly prone to thisproblem.

While some improvements in properties have been made, it would besignificant if it were possible to increase the stretching stiffness ofa styrene/diene block copolymer without increasing the plasticity. Whatis also desired is a polymer having an increased polarity, while alsohaving significantly lower melt and solution viscosity. Applicants havefound that these improvements can be achieved by designing a polymerhaving a different structure in the diene block, wherein undesirableblockiness is avoided and undesirable effects occurring duringpost-polymerization hydrogenation treatments are also reduced oravoided.

SUMMARY OF THE INVENTION

The present invention broadly comprises a block copolymer having atleast one A block and at least one B block, wherein:

-   -   a. each A block is a mono alkenyl arene polymer block and each B        block is a controlled distribution copolymer block of at least        one conjugated diene and at least one mono alkenyl arene;    -   b. each A block independently having a number average molecular        weight between about 3,000 and about 60,000 and each B block        independently having a number average molecular weight between        about 30,000 and about 300,000;    -   c. each B block comprises terminal regions adjacent to the A        block that are rich in conjugated diene units and one or more        regions not adjacent to the A blocks that are rich in mono        alkenyl arene units;    -   d. the total amount of mono alkenyl arene in the block copolymer        is about 20 percent weight to about 80 percent weight; and    -   e. the weight percent of mono alkenyl arene in each B block is        between about 10 percent and about 75 percent.        This block copolymer may be hydrogenated partially, selectively,        or fully. In a preferred embodiment the block copolymer will        have a Young's modulus of less than 2,800 psi (20 MPa) and a        rubber modulus or slope between 100 and 300% elongation of        greater than 70 psi (0.5 MPa). Such properties are not to be        found in polymers of the prior art.

Accordingly, in one aspect, the present invention relates to anunhydrogenated block copolymer having the general configuration A-B,A-B-A, (A-B)_(n), (A-B-A)_(n), (A-B-A)_(n)X, (A-B)_(n)X or mixturesthereof, where n is an integer from 2 to about 30, and X is couplingagent residue and wherein:

-   -   a. each A block is a mono alkenyl arene polymer block and each B        block is a controlled distribution copolymer block of at least        one conjugated diene and at least one mono alkenyl arene;    -   b. each A block having a number average molecular weight between        about 3,000 and about 60,000 and each B block having a number        average molecular weight between about 30,000 and about 300,000;    -   c. each B block comprises terminal regions adjacent to the A        block that are rich in conjugated diene units and one or more        regions not adjacent to the A blocks that are rich in mono        alkenyl arene units;    -   d. the total amount of mono alkenyl arene in the block copolymer        is about 20 percent weight to about 80 percent weight; and    -   e. the weight percent of mono alkenyl arene in each B block is        between about 10 percent and about 75 percent.

In another aspect, the present invention relates to a hydrogenated blockcopolymer having the general configuration A-B, A-B-A, (A-B)_(n),(A-B-A)_(n), (A-B-A)_(n)X, (A-B)_(n)X or mixtures thereof where n is aninteger from 2 to about 30, and X is coupling agent residue and wherein:

-   -   a. prior to hydrogenation each A block is a mono alkenyl arene        polymer block and each B block is a controlled distribution        copolymer block of at least one conjugated diene and at least        one mono alkenyl arene;    -   b. subsequent to hydrogenation about 0–10% of the arene double        bonds have been reduced, and at least about 90% of the        conjugated diene double bonds have been reduced;    -   c. each A block having a number average molecular weight between        about 3,000 and about 60,000 and each B block having a number        average molecular weight between about 30,000 and about 300,000;    -   d. each B block comprises terminal regions adjacent to the A        block that are rich in conjugated diene units and one or more        regions not adjacent to the A block that are rich in mono        alkenyl arene units;    -   e. the total amount of mono alkenyl arene in the hydrogenated        block copolymer is about 20 percent weight to about 80 percent        weight; and    -   f. the weight percent of mono alkenyl arene in each B block is        between about 10 percent and about 75 percent.        If desired the A blocks may also be fully saturated such that at        least about 90% of the arene double bonds have been reduced.        Also, if desired the saturation of the diene blocks may be        reduced such that anywhere from 25 to 95% of the diene double        bonds are reduced. Still further, it is also possible to        saturate only those double bonds that have a vinyl linkage.

In still another aspect, the present invention comprises a blockcopolymer having at least one A block, at least one B block and at leastone C block, wherein:

-   -   a. each A block is a mono alkenyl arene polymer block, each B        block is a controlled distribution copolymer block of at least        one conjugated diene and at least one mono alkenyl arene, and        each C block is a polymer block of one or more conjugated        dienes;    -   b. each A block having a number average molecular weight between        about 3,000 and about 60,000, each B block having a number        average molecular weight between about 30,000 and about 300,000,        and each C block having a number average molecular weight        between about 2,000 and about 200,000;    -   c. each B block comprises terminal regions adjacent to the A        block that are rich in conjugated diene units and one or more        regions not adjacent to the A blocks that are rich in mono        alkenyl arene units;    -   d. the total amount of mono alkenyl arene in the block copolymer        is about 20 percent weight to about 80 percent weight; and    -   e. the weight percent of mono alkenyl arene in each B block is        between about 10 percent and about 75 percent.        This block copolymer may also be hydrogenated selectively, fully        or partially.

In yet another aspect, the present invention comprises a tetrablockcopolymer having the structure A₁-B₁-A₂-B₂, wherein:

-   -   a. each A₁ and A₂ block is a mono alkenyl arene polymer block,        each B₁ block is a controlled distribution copolymer block of at        least one conjugated diene and at least one mono alkenyl arene,        and each B₂ block is selected from the group consisting of (I) a        controlled distribution copolymer block of at least one        conjugated diene and at least one mono alkenyl arene (ii) a        homopolymer block of a conjugated diene and (iii) a copolymer        block of two or more different conjugated dienes;    -   b. each A₁ and A₂ block having a number average molecular weight        between about 3,000 and about 60,000, each B₁ block having a        number average molecular weight between about 30,000 and about        300,000, and each B₂ block having a number average molecular        weight between 2,000 and 40,000;    -   c. each B₁ block comprises terminal regions adjacent to the A        block that are rich in conjugated diene units and one or more        regions not adjacent to the A blocks that are rich in mono        alkenyl arene units;    -   d. the total amount of mono alkenyl arene in the block copolymer        is about 20 percent weight to about 80 percent weight; and    -   e. the weight percent of mono alkenyl arene in each B₁ block is        between about 10 percent and about 75 percent.        This tetrablock copolymer may be hydrogenated selectively, fully        or partially.

Applicants also claim as their invention processes for making suchpolymers. One of the processes comprises:

-   -   a. polymerizing a mono alkenyl arene in a first reactor in the        presence of an inert hydrocarbon solvent and an organolithium        initiator whereby a living polymer block A1 terminated with a        lithium ion is formed;    -   b. adding to a second reactor an inert hydrocarbon solvent, 80        to 100% of the mono alkenyl arene monomer desired in the        copolymer block B1, between 10 and 60% of the conjugated diene        monomer desired in the copolymer block B1, and a distribution        agent;    -   c. transferring the living homopolymer block A1 to the second        reactor and starting the polymerization of the mono alkenyl        arene monomer and conjugated diene monomer added in step b; and    -   d. after about 5 to about 60 mol percent of the monomers of step        c have been polymerized, continuously adding the remaining        amount of conjugated diene monomer and mono alkenyl arene to the        second reactor at a rate that maintains the concentration of the        conjugated diene monomer at not less than about 0.1% weight        until about 90% of the monomers in block B1 have been        polymerized. It is preferable that less than 20% by weight of        the unreacted monomer present at the end of the continuous        addition be comprised of mono alkenyl arenes most preferable,        less than 15%, thereby forming a living block copolymer A1B1.

Another process of the present invention involves:

-   -   a. polymerizing a mono alkenyl arene in a first reactor in the        presence of an inert hydrocarbon solvent and an organolithium        initiator whereby a living polymer block A1 terminated with a        lithium ion is formed;    -   b. prior to the completion of the polymerization in step a,        adding to the reactor in one aliquot between 40 and 60% of the        conjugated diene monomer desired in the copolymer block B1, and        an effective amount of a distribution agent and continuing the        polymerization of the mono alkenyl arene monomer and conjugated        diene monomer;    -   c. after about 10 to about 60 mole % of the monomers of step b        have been polymerized, gradually adding the remaining amount of        conjugated diene monomer and mono alkenyl arene to the reactor        at a rate that maintains the concentration of the conjugated        diene monomer at no less than about 0.1% weight until about 90%        of the monomers in block B1 have been polymerized, thereby        forming a living copolymer block copolymer A1B1; and    -   d. adding additional mono alkenyl arene monomer to the reactor,        thereby forming a living copolymer A1B1A2, wherein the A1 block        and the A2 block each has a number average molecular weight of        about 3,000 to about 60,000 and the B1 block has a number        average molecular weight of about 30,000 to about 300,000.

In an alternative embodiment, the mono alkenyl arene monomer in block A1is polymerized to completion, and mono alkenyl arene monomer andconjugated diene monomer are charged simultaneously, but the monoalkenyl arene monomer is charged at a much faster rate.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1, 2 and 3 shows the distribution of styrene and butadiene in themidblock of three separate S—S/Bd-S block copolymers. As shown in theFigures, the controlled distribution copolymer block of the presentinvention is characterized by the presence of butadiene rich regions onthe ends of the block and styrene rich regions near the middle or centerof the controlled distribution block.

FIG. 4 is a plot of the tensile properties of block copolymers of thepresent invention containing styrene in the midblocks and havingcontrolled distribution compared to normal and high vinyl polymers. Allof the polymers in FIG. 4 had nominal block molecular weights of10,000-80,000–10,000.

FIG. 5 compares the stress-strain curves of a controlled distributionpolymer of the present invention against a commercial product withsimilar styrene contents, but not a controlled distribution.

DETAILED DESCRIPTION OF THE INVENTION

The present invention offers novel compositions and methods of preparingsuch in copolymerizing alkenyl arenes and dienes as part of a monoalkenyl arene/conjugated diene block copolymer. Surprisingly, thecombination of (1) a unique control for the monomer addition and (2) theuse of diethyl ether or other modifiers as a component of the solvent(which will be referred to as “distribution agents”) results in acertain characteristic distribution of the two monomers (herein termed a“controlled distribution” polymerization, i.e., a polymerizationresulting in a “controlled distribution” structure), and also results inthe presence of certain mono alkenyl arene rich regions and certainconjugated diene rich regions in the polymer block. For purposes hereof,“controlled distribution” is defined as referring to a molecularstructure having the following attributes: (1) terminal regions adjacentto the mono alkenyl arene homopolymer (“A”) blocks that are rich in(i.e., having a greater than average amount of) conjugated diene units;(2) one or more regions not adjacent to the A blocks that are rich in(i.e., having a greater than average amount of) mono alkenyl areneunits; and (3) an overall structure having relatively low blockiness.For the purposes hereof, “rich in” is defined as greater than theaverage amount, preferably greater than 5% the average amount. Thisrelatively low blockiness can be shown by either the presence of only asingle glass transition temperature (“Tg,”) intermediate between theTg's of either monomer alone, when analyzed using differential scanningcalorimetry (“DSC”) thermal methods or via mechanical methods, or asshown via proton nuclear magnetic resonance (“H-NMR”) methods. Thepotential for blockiness can also be inferred from measurement of theUV-visible absorbance in a wavelength range suitable for the detectionof polystyryllithium end groups during the polymerization of the Bblock. A sharp and substantial increase in this value is indicative of asubstantial increase in polystyryllithium chain ends. In this process,this will only occur if the conjugated diene concentration drops belowthe critical level to maintain controlled distribution polymerization.Any styrene monomer that is present at this point will add in a blockyfashion. The term “styrene blockiness”, as measured by those skilled inthe art using proton NMR, is defined to be the proportion of S units inthe polymer having two S nearest neighbors on the polymer chain. Thestyrene blockiness is determined after using H-1 NMR to measure twoexperimental quantities as follows:

First, the total number of styrene units (i.e. arbitrary instrumentunits which cancel out when ratioed) is determined by integrating thetotal styrene aromatic signal in the H-1 NMR spectrum from 7.5 to 6.2ppm and dividing this quantity by 5 to account for the 5 aromatichydrogens on each styrene aromatic ring.

Second, the blocky styrene units are determined by integrating thatportion of the aromatic signal in the H-1 NMR spectrum from the signalminimum between 6.88 and 6.80 to 6.2 ppm and dividing this quantity by 2to account for the 2 ortho hydrogens on each blocky styrene aromaticring. The assignment of this signal to the two ortho hydrogens on therings of those styrene units which have two styrene nearest neighborswas reported in F. A. Bovey, High Resolution NMR of Macromolecules(Academic Press, New York and London, 1972), chapter 6.

The styrene blockiness is simply the percentage of blocky styrene tototal styrene units:Blocky %=100 times (Blocky Styrene Units/Total Styrene Units)

Expressed thus, Polymer-Bd-S-(S)n-S-Bd-Polymer, where n is greater thanzero is defined to be blocky styrene. For example, if n equals 8 in theexample above, then the blockiness index would be 80%. It is preferredthat the blockiness index be less than about 40. For some polymers,having styrene contents of ten weight percent to forty weight percent,it is preferred that the blockiness index be less than about 10.

This controlled distribution structure is very important in managing thestrength and Tg of the resulting copolymer, because the controlleddistribution structure ensures that there is virtually no phaseseparation of the two monomers, i.e., in contrast with block copolymersin which the monomers actually remain as separate “microphases”, withdistinct Tg's, but are actually chemically bonded together. Thiscontrolled distribution structure assures that only one Tg is presentand that, therefore, the thermal performance of the resulting copolymeris predictable and, in fact, predeterminable. Furthermore, when acopolymer having such a controlled distribution structure is then usedas one block in a di-block, tri-block or multi-block copolymer, therelatively higher Tg made possible by means of the presence of anappropriately-constituted controlled distribution copolymer region willtend to improve flow and processability. Modification of certain otherproperties is also achievable.

In a preferred embodiment of the present invention, the subjectcontrolled distribution copolymer block has two distinct types ofregions—conjugated diene rich regions on the end of the block and a monoalkenyl arene rich region near the middle or center of the block. Whatis desired is a mono alkenyl arene/conjugated diene controlleddistribution copolymer block, wherein the proportion of mono alkenylarene units increases gradually to a maximum near the middle or centerof the block and then decreases gradually until the polymer block isfully polymerized. This structure is distinct and different from thetapered and/or random structures discussed in the prior art.

Anionic, solution copolymerization to form the controlled distributioncopolymers of the present invention can be carried out using, to a greatextent, known and previously employed methods and materials. In general,the copolymerization is attained anionically, using known selections ofadjunct materials, including polymerization initiators, solvents,promoters, and structure modifiers, but as a key feature of the presentinvention, in the presence of a certain distribution agent. Suchdistribution agent is, in preferred embodiments, a non-chelating ether.Examples of such ether compounds are cyclic ethers such astetrahydrofuran and tetrahydropyrane and aliphatic monoethers such asdiethyl ether and dibutyl ether. In some cases, particularly where thevinyl content of the conjugated diene is to be over 50%, it may benecessary to use a chelating agent, including dialkyl ethers of ethyleneglycol and aliphatic polyethers such as diethylene glycol dimethyl etherand diethylene glycol diethyl ether. Other distribution agents include,for example, ortho-dimethoxybenzene or “ODMB”, which is sometimesreferred to as a chelating agent. Preferably the ether is an aliphaticmonoether, and more preferably diethyl ether. Such copolymerization canbe conducted as a batch, semi-batch, or continuous preparation, withbatch being most preferred, but regardless, it is important that therandomization agent be present in the selected solvent prior to orconcurrent with the beginning of the copolymerization process.

The introduction of the distribution agent counteracts the preference ofthe growing chain end to attach to one monomer over another. Forexample, in the case of styrene and a diene, the preference would betoward the diene. This distribution agent operates to promote moreefficient “controlled distribution” copolymerization of the two monomersbecause the living chain end “sees” one monomer approximately as easilyas it “sees” the other. The polymerization process is thereby “tuned” toallow incorporation of each of the monomers into the polymer at nearlythe same rate. Such a process results in a copolymer having no “longruns” of either of the monomer components—in other words, a controlleddistribution copolymer as defined hereinabove. In the preferred process,the mono alkenyl arene monomer will be nearly consumed by the time thatthe slow addition of the second aliquot of diene is complete, so thatthe polymerization ends rich in the conjugated diene. Short blocks ofthe conjugated diene monomer may be formed throughout thepolymerization, but blocks of the mono alkenyl arene monomer are onlyformed when the concentration of the conjugated diene monomer becomesquite low. Under the preferred conditions, the cumulative percentage ofthe mono alkenyl arene monomer in the B block peaks at about 40%–60%overall conversion, but only exceeds the final value by about 25%–30%.The result of this relatively uniform distribution of monomers is aproduct having a single Tg, which is a weighted average of the Tg valuesof the two corresponding homopolymers.

As noted above, the distribution agent is preferably a non-chelatingether. By “non-chelating” is meant that such ethers will not chelatewith the growing polymer, that is to say, they will not form a specificinteraction with the chain end, which is derived from the initiatorcompound (e.g., lithium ion). Because the non-chelating ethers used inthe present invention operate by modifying the polarity of the entirepolymerization charge, they are preferably used in relatively largeconcentrations. Where diethyl ether, which is preferred, is selected, itis preferably at a concentration from about 0.5 to about 10 percent,preferably about 1 to about 10 percent, by weight of the polymerizationcharge (solvent and monomers), and more preferably from about 3 to about6 percent by weight. Higher concentrations of this monoether canalternatively be used, but appear to increase cost without addedefficacy. When the distribution agent is ODMB, the amount used istypically about 20 to about 400 parts by million weight (“PPMW”), basedon the total reactor contents, preferably about 20 to about 40 PPMW forlow vinyl products and about 100 to 200 PPMW for higher vinyl products.

An important aspect of the present invention is to control themicrostructure or vinyl content of the conjugated diene in thecontrolled distribution copolymer block. The term “vinyl content” refersto the fact that a conjugated diene is polymerized via 1,2-addition (inthe case of butadiene—it would be 3,4-addition in the case of isoprene).Although a pure “vinyl” group is formed only in the case of 1,2-additionpolymerization of 1,3-butadiene, the effects of 3,4-additionpolymerization of isoprene (and similar addition for other conjugateddienes) on the final properties of the block copolymer will be similar.The term “vinyl” refers to the presence of a pendant vinyl group on thepolymer chain. When referring to the use of butadiene as the conjugateddiene, it is preferred that about 20 to about 80 mol percent of thecondensed butadiene units in the copolymer block have 1,2 vinylconfiguration as determined by proton NMR analysis. For selectivelyhydrogenated block copolymers, preferably about 30 to about 70 molpercent of the condensed butadiene units should have 1,2 configuration.For unsaturated block copolymers, preferably about 20 to about 40 molpercent of the condensed butadiene units should have 1,2-vinylconfiguration. This is effectively controlled by varying the relativeamount of the distribution agent. As will be appreciated, thedistribution agent serves two purposes—it creates the controlleddistribution of the mono alkenyl arene and conjugated diene, and alsocontrols the microstructure of the conjugated diene. Suitable ratios ofdistribution agent to lithium are disclosed and taught in U.S. Pat. No.Re 27,145, which disclosure is incorporated by reference.

The solvent used as the polymerization vehicle may be any hydrocarbonthat does not react with the living anionic chain end of the formingpolymer, is easily handled in commercial polymerization units, andoffers the appropriate solubility characteristics for the productpolymer. For example, non-polar aliphatic hydrocarbons, which aregenerally lacking in ionizable hydrogens make particularly suitablesolvents. Frequently used are cyclic alkanes, such as cyclopentane,cyclohexane, cycloheptane, and cyclooctane, all of which are relativelynon-polar. Other suitable solvents will be known to one skilled in theart and can be selected to perform effectively in a given set of processconditions, with temperature being one of the major factors taken intoconsideration.

Starting materials for preparing the novel controlled distributioncopolymers of the present invention include the initial monomers. Thealkenyl arene can be selected from styrene, alpha-methylstyrene,para-methylstyrene, vinyl toluene, vinylnaphthalene, and para-butylstyrene or mixtures thereof. Of these, styrene is most preferred and iscommercially available, and relatively inexpensive, from a variety ofmanufacturers. The conjugated dienes for use herein are 1,3-butadieneand substituted butadienes such as isoprene, piperylene,2,3-dimethyl-1,3-butadiene, and 1-phenyl-1,3-butadiene, or mixturesthereof. Of these, 1,3-butadiene is most preferred. As used herein, andin the claims, “butadiene” refers specifically to “1,3-butadiene”.

Other important starting materials for anionic copolymerizations includeone or more polymerization initiators. In the present invention suchinclude, for example, alkyl lithium compounds and other organolithiumcompounds such as s-butyllithium, n-butyllithium, t-butyllithium,amyllithium and the like, including di-initiators such as thedi-sec-butyl lithium adduct of m-diisopropenyl benzene. Other suchdi-initiators are disclosed in U.S. Pat. No. 6,492,469. Of the variouspolymerization initiators, s-butyllithium is preferred. The initiatorcan be used in the polymerization mixture (including monomers andsolvent) in an amount calculated on the basis of one initiator moleculeper desired polymer chain. The lithium initiator process is well knownand is described in, for example, U.S. Pat. Nos. 4,039,593 and Re.27,145, which descriptions are incorporated herein by reference.

Polymerization conditions to prepare the novel copolymers of the presentinvention are typically similar to those used for anionicpolymerizations in general. In the present invention polymerization ispreferably carried out at a temperature of from about −30° to about 150°C., more preferably about 10° to about 100° C., and most preferably, inview of industrial limitations, about 30° to about 90° C. It is carriedout in an inert atmosphere preferably nitrogen, and may also beaccomplished under pressure within the range of from about 0.5 to about10 bars. This copolymerization generally requires less than about 12hours, and can be accomplished in from about 5 minutes to about 5 hours,depending upon the temperature, the concentration of the monomercomponents, the molecular weight of the polymer and the amount ofdistribution agent that is employed.

As discussed above, an important discovery of the present invention isthe control of the monomer feed during the polymerization of thecontrolled distribution block. To minimize blockiness, it is desirableto polymerize as much of the styrene as possible in the presence ofbutadiene. Towards that end, a preferred process adds the styrene chargeas quickly as possible, while adding the butadiene slowly, so as tomaintain a concentration of no less than about 0.1% wt of butadiene foras long as possible, preferably until the styrene is nearly exhausted.If the butadiene falls below this level, there is a risk that a styreneblock will form at this point. It is generally undesirable to form astyrene block during the butadiene charge portion of the reaction.

In a two—reactor polymerization scheme, this is most readilyaccomplished by adding about 80 to 100 percent of the mono alkenyl areneto the second reactor, along with about 10 to about 60 percent of theconjugated diene. The monomers are then caused to start polymerizationvia transfer of the living polymer from the first reactor. After about 5to 60 mol percent of the monomers have polymerized, the remainingportion of the mono alkenyl arene (if any) is added and the remainingconjugated diene monomer is added at a rate that maintains theconcentration of the conjugated diene monomer at no less than about 0.1%weight. The rate of diene monomer addition will be determined by thestyrene content of the midblock, the reaction temperature and the typeand concentration of the distribution control agent used. Reaction ratesare relatively fast in the presence of 6%–10% diethyl ether. In thissystem, the diene is typically charged over 15 to 60 minutes. Rates forboth monomers are slower in the presence of 0.5%–1% diethyl ether or35–40 PPM o-dimethoxybenzene. In this solvent system, it is more typicalto add the diene over 60 to 90 minutes. The higher the midblock styrene,the more advantageous it is to add the diene slowly. If the polymer isto be prepared in a fully sequential process, it is preferable to ensurethat the butadiene addition continues until about 90% of the monomers inblock B1 have been polymerized, and the percentage of the mono alkenylarene monomer in the non-reacted monomer pool has been reduced to lessthan 20% weight, preferably less than 15% weight. In this way theformation of styrene blocks is prevented throughout the majority of thepolymerization and there is sufficient conjugated diene left at the endof the polymerization to ensure that the terminal region of the B1 blockis richer in the diene monomer. The resulting polymer block has dienerich regions near the beginning and the end of the block and an arenerich region near the center of the block. In products of the preferredprocess, typically the first 15 to 25% and the last 75 to 85% of theblock are diene rich, with the remainder considered to be arene rich.The term “diene rich” means that the region has a measurably higherratio of diene to arene than the center region. Another way to expressthis is the proportion of mono alkenyl arene units increases graduallyalong the polymer chain to a maximum near the middle or center of theblock and then decreases gradually until the polymer block is fullypolymerized. In a preferred embodiment, all of the mono alkenyl areneand about 10 to 20 percent of the conjugated diene are charged to thereactor, and the remainder of the conjugated diene is added after about5 to about 10 percent of the original monomers have polymerized.

It is typically possible to achieve the desired distribution of thearene monomer in the final product using the process described above iffairly high levels of the distribution control agent are used. At highermidblock styrene levels and low levels of the distribution controlagent, some blockiness is unavoidable. It is preferable to prepare theseproducts by coupling. This insures that any blocky styrene that isformed is located at some distance from the endblocks. When polymers ofthe present invention are prepared by coupling, it is preferable toreserve 5% to 10% of the diene monomer, and add this charge once thepolymerization of the arene monomer is complete. This ensures that allof the chains end in a diene unit. The living diene chain ends generallyreact more efficiently with coupling agents.

If the products of the present invention are being prepared in a singlereactor process in which all of the B1 monomer is charged to a reactorcontaining the living A block, it is preferable to start the dienemonomer addition about 1 minute before starting the arene monomeraddition. It is also preferable to charge both monomers rapidly at firstand then decrease the diene addition rate once the majority of the arenemonomer has been added. This process ensures that the initial region ofthe B1 block will be rich in the diene monomer, and builds a largeenough pool to avoid becoming starved in the diene monomer early inprocess step. As discussed above, the optimal rates will depend on thestyrene content of the midblock, the reaction temperature and the typeand concentration of the distribution control agent used.

For the controlled distribution or B block the weight percent of monoalkenyl arene in each B block is between about 10 weight percent andabout 75 weight percent, preferably between about 25 weight percent andabout 50 weight percent for selectively hydrogenated polymers.

As used herein, “thermoplastic block copolymer” is defined as a blockcopolymer having at least a first block of one or more mono alkenylarenes, such as styrene and a second block of a controlled distributioncopolymer of diene and mono alkenyl arene. The method to prepare thisthermoplastic block copolymer is via any of the methods generally knownfor block polymerizations. The present invention includes as anembodiment a thermoplastic copolymer composition, which may be either adi-block, tri-block copolymer, tetra-block copolymer or multi-blockcomposition. In the case of the di-block copolymer composition, oneblock is the alkenyl arene-based homopolymer block and polymerizedtherewith is a second block of a controlled distribution copolymer ofdiene and alkenyl arene. In the case of the tri-block composition, itcomprises, as end-blocks the glassy alkenyl arene-based homopolymer andas a mid-block the controlled distribution copolymer of diene andalkenyl arene. Where a tri-block copolymer composition is prepared, thecontrolled distribution diene/alkenyl arene copolymer can be hereindesignated as “B” and the alkenyl arene-based homopolymer designated as“A”. The A-B-A, tri-block compositions can be made by either sequentialpolymerization or coupling. In the sequential solution polymerizationtechnique, the mono alkenyl arene is first introduced to produce therelatively hard aromatic block, followed by introduction of thecontrolled distribution diene/alkenyl arene mixture to form the midblock, and then followed by introduction of the mono alkenyl arene toform the terminal block. In addition to the linear, A-B-A configuration,the blocks can be structured to form a radial (branched) polymer,(A-B)_(n)X, or both types of structures can be combined in a mixture. Inaddition it is contemplated that asymmetrical, polymodal blockcopolymers are included, where some of the A blocks have highermolecular weights than some of the other A blocks—e.g., such a polymercould have the structure (A₁-B)_(d)-X-_(e)(B-A₂) where d is 1 to 30 ande is 1 to 30, and the molecular weight of A1 and A2 blocks differ by atleast 20 percent. Some A-B diblock polymer can be present but preferablyat least about 70 weight percent of the block copolymer is A-B-A orradial (or otherwise branched so as to have 2 or more terminal resinousblocks per molecule) so as to impart strength.

Preparation of radial (branched) polymers requires a post-polymerizationstep called “coupling”. In the above radial formula n is an integer offrom 2 to about 30, preferably from about 2 to about 15, and X is theremnant or residue of a coupling agent. A variety of coupling agents areknown in the art and include, for example, dihalo alkanes, siliconhalides, siloxanes, multifunctional epoxides, silica compounds, estersof monohydric alcohols with carboxylic acids, (e.g. dimethyl adipate)and epoxidized oils. Star-shaped polymers are prepared with polyalkenylcoupling agents as disclosed in, for example, U.S. Pat. Nos. 3,985,830;4,391,949; and 4,444,953; Canadian Patent Number 716,645. Suitablepolyalkenyl coupling agents include divinylbenzene, and preferablym-divinylbenzene. Preferred are tetra-alkoxysilanes such astetra-ethoxysilane (TEOS), aliphatic diesters such as dimethyl adipateand diethyl adipate, and diglycidyl aromatic epoxy compounds such asdiglycidyl ethers deriving from the reaction of bis-phenol A andepichlrohydrin.

Additional possible post-polymerization treatments that can be used tofurther modify the configuration of the polymers and therefore theirproperties include capping and chain-termination. Capping agents, suchas ethylene oxide, carbon dioxide, or mixtures thereof serve to addfunctional groups to the chain ends, where they can then serve asreaction sites for further property-modifying reactions. In contrast,chain termination simply prevents further polymerization and thusprevents molecular weight growth beyond a desired point. This isaccomplished via the deactivation of active metal atoms, particularlyactive alkali metal atoms, and more preferably the active lithium atomsremaining when all of the monomer has been polymerized. Effective chaintermination agents include water; alcohols such as methanol, ethanol,isopropanol, 2-ethylhexanol, mixtures thereof and the like; andcarboxylic acids such as formic acid, acetic acid, maleic acid, mixturesthereof and the like. See, for example, U.S. Pat. No. 4,788,361, thedisclosure of which is incorporated herein by reference. Other compoundsare known in the prior art to deactivate the active or living metal atomsites, and any of these known compounds may also be used. Alternatively,the living copolymer may simply be hydrogenated to deactivate the metalsites.

The polymerization procedures described hereinabove, includingpreparation of the diene/alkenyl arene copolymer and of di-block andmulti-block copolymers prepared therewith, can be carried out over arange of solids content, preferably from about 5 to about 80 percent byweight of the solvent and monomers, most preferably from about 10 toabout 40 weight percent. For high solids polymerizations, it ispreferable to add any given monomer, which may include, as previouslynoted, a previously prepared homopolymer or copolymer, in increments toavoid exceeding the desired polymerization temperature. Properties of afinal tri-block polymer are dependent to a significant extent upon theresulting alkenyl content and diene content. It is preferred that, toensure significantly elastomeric performance while maintaining desirablyhigh Tg and strength properties, as well as desirable transparency, thetri-block and multi-block polymer's alkenyl arene content is greaterthan about 20% weight, preferably from about 20% to about 80% weight.This means that essentially all of the remaining content, which is partof the diene/alkenyl arene block, is diene.

It is also important to control the molecular weight of the variousblocks. For an AB diblock, desired block weights are 3,000 to about60,000 for the mono alkenyl arene A block, and 30,000 to about 300,000for the controlled distribution conjugated diene/mono alkenyl arene Bblock. Preferred ranges are 5000 to 45,000 for the A block and 50,000 toabout 250,000 for the B block. For the triblock, which may be asequential ABA or coupled (AB)₂ X block copolymer, the A blocks shouldbe 3,000 to about 60,000, preferably 5000 to about 45,000, while the Bblock for the sequential block should be about 30,000 to about 300,000,and the B blocks (two) for the coupled polymer half that amount. Thetotal average molecular weight for the triblock copolymer should be fromabout 40,000 to about 400,000, and for the radial copolymer from about60,000 to about 600,000. For the tetrablock copolymer ABAB the blocksize for the terminal B block should be about 2,000 to about 40,000, andthe other blocks may be similar to that of the sequential triblockcopolymer. These molecular weights are most accurately determined bylight scattering measurements, and are expressed as number averagemolecular weight.

An important feature of the thermoplastic elastomeric di-block,tri-block and tetra-block polymers of the present invention, includingone or more controlled distribution diene/alkenyl arene copolymer blocksand one or more mono alkenyl arene blocks, is that they have at leasttwo Tg's, the lower being the single Tg of the controlled distributioncopolymer block which is an intermediate of its constituent monomers'Tg's. Such Tg is preferably at least about −60 degrees C., morepreferably from about −40 degrees C. to about +30 degrees C., and mostpreferably from about −40 degrees C. to about +10 degrees C. The secondTg, that of the mono alkenyl arene “glassy” block, is preferably fromabout +80 degrees C. to about +110 degrees C., more preferably fromabout +80 degrees C. to about +105 degrees C. The presence of the twoTg's, illustrative of the microphase separation of the blocks,contributes to the notable elasticity and strength of the material in awide variety of applications, and its ease of processing and desirablemelt-flow characteristics.

It should be noted that, in yet another embodiment of the presentinvention, additional property improvements of the compositions hereofcan be achieved by means of yet another post-polymerization treatment,that of hydrogenation of the block copolymer. The preferredhydrogenation is selective hydrogenation of the diene portions of thefinal block copolymer. Alternatively both the B blocks and the A blocksmay be hydrogenated, or merely a portion of the B blocks may behydrogenated. Hydrogenation generally improves thermal stability,ultraviolet light stability, oxidative stability, and, therefore,weatherability of the final polymer. A major advantage of the presentinvention is that the distribution agent, such as the non-chelatingmonoether, which is present during the initial polymerization process,does not interfere with or otherwise “poison” the hydrogenationcatalyst, and thus the need for any additional removal steps isobviated.

Hydrogenation can be carried out via any of the several hydrogenation orselective hydrogenation processes known in the prior art. For example,such hydrogenation has been accomplished using methods such as thosetaught in, for example, U.S. Pat. Nos. 3,595,942; 3,634,549; 3,670,054;3,700,633; and Re. 27,145, the disclosures of which are incorporatedherein by reference. These methods operate to hydrogenate polymerscontaining aromatic or ethylenic unsaturation and are based uponoperation of a suitable catalyst. Such catalyst, or catalyst precursor,preferably comprises a Group VIII metal such as nickel or cobalt whichis combined with a suitable reducing agent such as an aluminum alkyl orhydride of a metal selected from Groups I-A, II-A and III-B of thePeriodic Table of the Elements, particularly lithium, magnesium oraluminum. This preparation can be accomplished in a suitable solvent ordiluent at a temperature from about 20° C. to about 80° C. Othercatalysts that are useful include titanium based catalyst systems.

Hydrogenation can be carried out under such conditions that at leastabout 90 percent of the conjugated diene double bonds have been reduced,and between zero and 10 percent of the arene double bonds have beenreduced. Preferred ranges are at least about 95 percent of theconjugated diene double bonds reduced, and more preferably about 98percent of the conjugated diene double bonds are reduced. Alternatively,it is possible to hydrogenate the polymer such that aromaticunsaturation is also reduced beyond the 10 percent level mentionedabove. Such exhaustive hydrogenation is usually achieved at highertemperatures. In that case, the double bonds of both the conjugateddiene and arene may be reduced by 90 percent or more.

Once the hydrogenation is complete, it is preferable to extract thecatalyst by stirring with the polymer solution a relatively large amountof aqueous acid (preferably 20–30 percent by weight), at a volume ratioof about 0.5 parts aqueous acid to 1 part polymer solution. Suitableacids include phosphoric acid, sulfuric acid and organic acids. Thisstirring is continued at about 50° C. for about 30 to about 60 minuteswhile sparging with a mixture of oxygen in nitrogen. Care must beexercised in this step to avoid forming an explosive mixture of oxygenand hydrocarbons.

In an alternative, the block copolymer of the present invention may befunctionalized in a number of ways. One way is by treatment with anunsaturated monomer having one or more functional groups or theirderivatives, such as carboxylic acid groups and their salts, anhydrides,esters, imide groups, amide groups, and acid chlorides. The preferredmonomers to be grafted onto the block copolymers are maleic anhydride,maleic acid, fumaric acid, and their derivatives. A further descriptionof functionalizing such block copolymers can be found in Gergen et al,U.S. Pat. No. 4,578,429 and in U.S. Pat. No. 5,506,299. In anothermanner, the selectively hydrogenated block copolymer of the presentinvention may be functionalized by grafting silicon or boron containingcompounds to the polymer as taught in U.S. Pat. No. 4,882,384. In stillanother manner, the block copolymer of the present invention may becontacted with an alkoxy-silane compound to form silane-modified blockcopolymer. In yet another manner, the block copolymer of the presentinvention may be functionalized by grafting at least one ethylene oxidemolecule to the polymer as taught in U.S. Pat. No. 4,898,914, or byreacting the polymer with carbon dioxide as taught in U.S. Pat. No.4,970,265. Still further, the block copolymers of the present inventionmay be metallated as taught in U.S. Pat. Nos. 5,206,300 and 5,276,101,wherein the polymer is contacted with an alkali metal alkyl, such as alithium alkyl. And still further, the block copolymers of the presentinvention may be functionalized by grafting sulfonic groups to thepolymer as taught in U.S. Pat. No. 5,516,831. All of the patentsmentioned in this paragraph are incorporated by reference into thisapplication.

The last step, following all polymerization(s) as well as any desiredpost-treatment processes, is a finishing treatment to remove the finalpolymer from the solvent. Various means and methods are known to thoseskilled in the art, and include use of steam to evaporate the solvent,and coagulation of the polymer followed by filtration. The final resultis a “clean” block copolymer useful for a wide variety of challengingapplications, according to the properties thereof. These propertiesinclude, for example, the final polymer's stress-strain response, whichshows that a composition of the present invention exhibits a stifferrubbery response to strain, therefore requiring more stress to extendthe same length. This is an extremely useful property that allows theuse of less material to achieve the same force in a given product.Elastic properties are also modified, exhibiting increasing modulus withincreasing elongation, and there is a reduced occurrence of the rubberyplateau region where large increases in elongation are required toprocure an increase in stress. Another surprising property is increasedtear strength. The controlled distribution copolymers of the presentinvention offer additional advantage in their ability to be easilyprocessed using equipment generally designed for processingthermoplastic polystyrene, which is one of the most widely known andused alkenyl arene polymer. Melt processing can be accomplished viaextrusion or injection molding, using either single screw or twin screwtechniques that are common to the thermoplastics industry. Solution orspin casting techniques can also be used as appropriate.

The polymers of the present invention are useful in a wide variety ofapplications including, for example, molded and extruded goods such astoys, grips, handles, shoe soles, tubing, sporting goods, sealants,gaskets, and oil gels. The compositions also find use as rubbertoughening agents for polyolefins, polyamides, polyesters and epoxyresins. Improved elasticity when compared with conventional styrenicblock copolymers makes these copolymers particularly useful foradhesives, including both pressure-sensitive and hot-melt adhesives.

A particularly interesting application is thermoplastic films whichretain the processability of styrenic block copolymers but exhibit ahigher “elastic power” similar to spandex polyurethanes. As compoundedwith polyethylene or with a combination of tackifying resin andpolyethylene, the controlled distribution copolymers of the presentinvention can meet these performance expectations. The resultant filmsshow significant improvements in puncture resistance and strength, andreduced viscosity, when compared with common styrene/ethylene-butyleneblock copolymers. The same controlled distribution styrene/butadiene(20/80 wt/wt) copolymer can also be formulated in a film compound withoil and polystyrene, wherein it exhibits higher strength and improvedenergy recovery and transparency in comparison with a controlformulation based on a styrene/ethylene-butylene/styrene blockcopolymer. In molding applications formulated using oil andpolypropylene, reduced viscosity and coefficients of friction also offerexpansion in applications such as cap seals, which may be able to beproduced without undesirable slip agents which may bloom and contaminatecontents.

Finally, the copolymers of the present invention can be compounded withother components not adversely affecting the copolymer properties.Exemplary materials that could be used as additional components wouldinclude, without limitation, pigments, antioxidants, stabilizers,surfactants, waxes, flow promoters, solvents, particulates, andmaterials added to enhance processability and pellet handling of thecomposition.

The following examples are intended to be illustrative only, and are notintended to be, nor should they be construed as being, limitative in anyway of the scope of the present invention

Illustrative Embodiment #1

In Illustrative Embodiment #1, various controlled distributioncopolymers of the present invention were prepared according to theprocess claimed herein. All polymers were selectively hydrogenated ABAblock copolymers where the A blocks were polystyrene blocks and the Bblock prior to hydrogenation was a styrene/butadiene controlleddistribution block copolymer having terminal regions that are rich inbutadiene units and a center region that was rich in styrene units. Thepolymers were hydrogenated under standard conditions such that greaterthan 95% of the diene double bonds in the B block have been reduced.

The following describes the general procedure used to effectivelycontrol the distribution of the comonomers in the anioniccopolymerization of 1,3-butadiene (Bd) and styrene (S) in the presenceof diethyl ether (DEE). A number of tri-block copolymers weresynthesized stepwise in cyclohexane. Di-ethyl ether (“DEE”) was used tocontrol the distribution of copolymerization of styrene and butadiene inthe rubber midblock. During the copolymerization step, a number ofsamples were collected as the reaction progressed to enable H-NMRcharacterization of the degree of comonomer distribution.

For Step I, an appropriate amount of polymerization grade cyclohexanewas charged to a well-mixed 227 liter stainless steel reactor vessel at30° C. Pressure in the reactor vessel was controlled with nitrogen gas.Styrene monomer was charged to the reactor at 30° C. 10 ml increments ofsec-butyllithium (12 wt.) were added to the reactor to titrate thecyclohexane and styrene monomer mixture. The titration endpoint wasdetermined with an on-line colorimeter. After titration,sec-butyllithium was then added to the reactor to initiate the anionicpolymerization of the living polystyrene blocks. The temperature wasallowed to increase to 55° C. and the reaction was carried out to 99.9%conversion of the styrene. This completed the first styrene block ofthis block copolymer, (S)—.

For Step II, an appropriate amount of polymerization grade cyclohexanewas charged to a well-mixed 492 liter stainless steel reactor vessel at30° C. First, all of the styrene monomer required in the Step IIreaction was charged to the reactor. Second, one-half of the butadienemonomer required in the Step II reaction was charged to the reactor.Third, an appropriate amount of diethyl ether was charged to thereactor. Fourth, 10 ml increments of sec-butyllithium (12% wt.) wereadded to the reactor to titrate the cyclohexane, styrene monomer,butadiene monomer and diethyl ether mixture. The titration endpoint wasdetermined with an on-line colorimeter. After titration of the Step IIrecatonts, the living polystyrene chains were transferred via nitrogenpressure from the Step I reactor vessel to the Step II reactor vessel toinitiate the Step II copolymerization reaction of styrene and butadieneat 30° C. Ten minutes after the initiation of the copolymerization, theremaining one-half of the butadiene monomer was dosed to the Step IIreactor at a rate that kept the overall polymerization rate nearlyconstant. The temperature was allowed to increase to 55° C. and thereaction was carried out to 99.9% conversion basis butadiene kinetics.This completed the addition of a styrene-butadiene randomized midblockto the Step I polystyrene block. The polymer structure at this point is(S)—(S/Bd)-.

For Step III, more styrene monomer was charged to the Step II reactorvessel at 55° C. to react with the living (S)—(S/Bd)-polymer chains. TheStep III reaction was maintained at near isothermal conditions until99.9% conversion of the styrene. The living polymer chains wereterminated by adding an appropriate amount (about 10% molar excess) ofhigh-grade methanol to the final reactor solution. The final polymerstructure was (S)—(S/Bd)-(S). All polymers were then selectivelyhydrogenated to produce linear ABA block copolymers where the A blockswere polystyrene blocks and the B block prior to hydrogenation was astyrene butadiene controlled distribution block having terminal regionsthat are rich in butadiene units and a center region that was rich instyrene units. The various polymers are shown in Table 1 below. Step IMW is the molecular weight of the first A block, Step II MW is themolecular weight of the AB blocks and Step III MW is the molecularweight of the ABA blocks. The polymers were hydrogenated such thatgreater than about 95% of the diene double bonds have been reduced.

This type of experiment was executed 19 times over a range of varyingstyrene-butadiene midblock compositions. The analytical results fromeach of the 19 experiments (polymers 1 to 15 and 24 to 27) are given inTable 1 and Table 1a. The conditions for polymerization for each of thefirst 8 experiment are given in Table 2. The conditions forpolymerization of the other 11 polymers were similar to those for thefirst 8. Table 3 shows the polymer architecture for the variouspolymers. Polymer 28 is selectively hydrogenated AB diblock copolymer.Where the polystyrene A block is polymerized first, followed by therequested polymerization of the controlled distributionstyrene/butadiene B block, followed by hydrogenation of the diene doublebonds.

The following describes the method used to characterize the polymer midor “B” block. It is the nature of the polymerization that the polymermid-block is formed after an initial styrene block. Since the polymermid-block which is formed in Step II cannot be analyzed in isolation, itmust be analyzed in combination with the Step I styrene block, and thecontribution of the Step I styrene block must be subtracted from the sumto determine the parameters which characterize the polymer mid-block.Four experimental quantities are used to calculate the percent styrenecontent in the polymer mid-block (Mid PSC) and the percent blockystyrene in the polymer mid-block (Mid Blocky). (Note: % BD12 for themid-block is measured directly with no need to correct for a BDcontribution from the Step I styrene block). The experimental quantitiesand the method of calculation will be illustrated using polymer example#15. The four key experimental quantities for polymer example #15 are:

GPC Step I MW: 9.0 k GPC Step II MW: 86.8 k NMR Step II PSC: 33.4 wt %NMR Step II blocky styrene: 33%where Step I consists of the Step I styrene block, and Step II is thecombination of the Step I styrene block and the styrene/butadienemid-block.

The total styrene mass in Step II is given by:33.4 wt % of 86.8 k=29.0 k styrene in Step IIThe styrene mass of the mid-block is found by subtracting the Step Istyrene mass from the styrene in Step II:29.0 k−9.0 k=20.0 k styrene in mid-blockThe mass of the mid-block is given by subtracting the Step I MW from theStep II MW:86.8 k−9.0 k=77.8 k mass if mid-blockThe “Mid PSC” is the percent of mid-block styrene relative to themid-block mass:100*20.0 k mid-block styrene/77.8 k mid-block mass=25.7 wt %

The blocky styrene % and the Step II styrene mass give the mass ofblocky styrene:33% of 29.0 k=9.6 k Step II blocky styreneThe Step I styrene block is subtracted from the mass of Step II blockystyrene to give the mass of blocky styrene in the mid-block:9.6 k Step II blocky styrene−9.0 k Step I styrene block=0.6 kThe “Mid Blocky” is the percent of blocky styrene in the mid-blockrelative to the styrene in the mid-block:100*0.6 k mid-block blocky styrene/20.0 k mid-block styrene=3%The calculated value for styrene blockiness in the B mid-block (“MidBlocky”) for all polymers described in this Illustrative Embodiment isshown in Table 1a. Also shown is the calculated percent styrene in eachB mid-block (“Calc. Mid PSC”).

FIGS. 1, 2 and 3 depict the monomer distribution in the Bd/S block of 3of the polymers prepared in this embodiment. The data in these figureswas obtained by taking aliquots of the living polymerization solution atvarious times during the synthesis of the Step II block of the S—S/Bd-Spreparations, that is during the controlled distributioncopolymerization of butadiene and styrene portion of the block copolymerpreparation. The polybutadiene and polystyrene compositions of each ofthese aliquots was measured using an H-NMR technique. These “raw data”were adjusted by subtracting out the polystyrene component of the Step Ipolystyrene block from cumulative polystyrene content of the aliquot.The remainder gave the polystyrene component of the Step II block foreach aliquot. The ratio of the polybutadiene content in moles to thepolystyrene content in moles (as calculated in this way) was plottedagainst the level of conversion for each of the aliquots in each of theexperiments. The molecular weight of the Step II block for each of thealiquots was obtained by subtracting the molecular weight of the Step Iblock from the molecular weight of the aliquot. The molecular weight ofthe Step II block for the final aliquot was taken as the total molecularweight for this region (100% conversion). The level of conversion ofeach of the aliquots was calculated by taking the ratio of the Step IImolecular weight for that aliquot to the molecular weight of the finalStep II aliquot for that polymerization.

These plots clearly show the benefit of the present invention. Thecontrolled distribution polymerization, in each case, starts out andends with a relatively high ratio of incorporated butadiene to styrene(butadiene rich). Clearly there are no runs of polystyrene on either endof the Step II region, thus the control of end block molecular weight isdetermined only by the size the Step I and Step III styrene charges andthe number of living chain ends in those polymerization Steps. The StepI and Step III polystyrene block sizes are not augmented by the additionof polystyrene runs at the start nor at the end of the Step IIpolymerization.

It is significant to note that even though the center portion of theStep II regions in each of these polymerizations was richer in styrene(had a lower Bd/S ratio) there still were few, if any, styrenemultiplets (<10 mol % of the styrene) incorporated into the polymerchain during this stage of the polymerization, as analyzed by H-NMR. Acontrolled distribution incorporation of the styrene monomer into thepolymer chain was observed even though the relative rate ofincorporation of styrene to butadiene had increased during this part(from about 40% to about 60% conversion of the Step II polymerization)of the polymerization. Such a controlled distribution incorporation ofstyrene in these copolymerization reactions seems to be necessary toobtain the desired stiffer stretch performance in the selectivelyhydrogenated S—S/Bd-S (also known as S—S/E/B—S orstyrene-styrene/ethylene/butylene-styrene) product block copolymers.

Illustrative Embodiment #II

In Illustrative Embodiment II various polymers of the present inventionare compared against polymers of the prior art. All the polymers werelinear selectively hydrogenated ABA block copolymers made with styreneand butadiene monomers, and had nominal or target molecular weights of10,000 for each of the A end blocks and 80,000 for the B mid block.Polymers 2 and 3 from Illustrative Embodiment I were used in thisexample. Polymers C-1 and C-2 are for comparison, and do not have anystyrene in the B mid block. C-1 has a higher vinyl 1,2 content of 68%,while C-2 has a vinyl 1,2 content of 38%. Polymer C-3 was prepared withabout 23 percent weight styrene in the B mid block. Polymer C-3 wasprepared in a conventional polymerization process, wherein the mid blockwas prepared by co-polymerization of butadiene and styrene with achelating agent, and without controlled addition of the butadiene andstyrene monomers. Rather, all the butadiene and styrene were added tothe reactor at the start of the mid block polymerization along with themicrostructure modifying agent (1,2 diethoxy propane). Accordingly,Polymer C-3 does not have a “controlled distribution” structure. Detailson the block molecular weights and vinyl 1,2 contents are shown in Table4.

Films were prepared from the polymers and tensile tested according toASTM D412, and the results are shown in Table 5. One of the objectivesof the current invention is to make polymers that have a stiffer elasticresponse than Polymer C-2, a polymer that is well known in the art. Itis the objective of the current invention to increase the rubberstiffness at elongations above 100% thus increasing the elastic power,while producing a limited increase in Young's Modulus, the stiffness atinfinitesimal elongations. Increasing the Young's modulus is detrimentalto elastomeric performance because it signifies an increase inplasticity. Increasing the vinyl content without the controlled additionof styrene to block B, as shown in Polymer C-1, reduces the stiffness atlow and high elongations as shown in FIG. 4. Table 5 shows numericallythat increasing the vinyl content reduces both the Young's Modulus, thestiffness at infinitesimal elongations, and the rubber modulus, therubber stiffness at higher elongations between 100 and 300%. Addingstyrene to the midblock in a controlled distribution, however, increasesthe rubber stiffness as shown in FIG. 4 and table 5, with a smallincrease in Young's modulus. The importance of controlling thedistribution of styrene in the B mid block is illustrated by PolymerC-3. Although it is similar in composition to Polymer 3, its rubbermodulus is not increased compared to C-2, the standard of the currentart, while its Young's modulus is significantly increased, thus itsuffers from both lower elastic power and greater plasticity. The 500%modulus in Table 5 demonstrates this response as well. The polymers ofthe present invention—Polymers 2 and 3—exhibit stiffer elastic behavioras shown by FIG. 4 and the 500% modulus in Table 5.

Illustrative Embodiment #III

In Illustrative Embodiment # III, a general procedure was used toeffectively control the styrene distribution during the anioniccopolymerization of 1,3-butadiene (Bd) and styrene (S) in the presenceof diethyl ether (DEE), di-n-butyl ether (nBE) or o-dimethoxybenzene(ODMB) while maintaining a low enough vinyl content to produce usefulunsaturated products. A number of block copolymer mixtures of(S—S/Bd)_(n)X linear/radial block copolymers were synthesized bycoupling of the living S—S/BdLi diblock with tetraethoxy silane (TEOS).In some cases, a number of samples were collected as thecopolymerization reaction progressed to enable H-NMR characterization ofthe distribution of the monomers. Process data corresponding to specificreactions is summarized in Table 6.

For Step I, an appropriate amount of polymerization grade cyclohexanewas charged to a well-mixed 227-liter stainless steel reactor vessel at30° C. Pressure in the reactor vessel was controlled with nitrogen gas.Styrene monomer was charged to the reactor at 30° C. 10 ml increments ofsec-butyllithium (12% wt.) were added to the reactor to titrate thecyclohexane and styrene monomer mixture. The titration endpoint wasdetermined with an on-line colorimeter. After titration, a gig of excesssec-butyllithium was then added to the reactor to initiate the anionicpolymerization of the living polystyrene blocks. The temperature wasallowed to increase to 55° C. and the reaction was carried out to 99.9%conversion of the styrene. This completed the first styrene block ofthis block copolymer, (S)—.

For Step II, an appropriate amount of polymerization grade cyclohexanewas charged to a well-mixed 492 liter stainless steel reactor vessel at30° C. First, all of the styrene monomer required in the Step IIreaction was charged to the reactor. Second, a fraction of the butadienemonomer required in the Step II reaction was charged to the reactor.Third, an appropriate amount of the distribution agent was charged tothe reactor. Fourth, 10 ml increments of sec-butyllithium (12% wt.) wereadded to the reactor to titrate the cyclohexane, styrene monomer,butadiene monomer and modifier mixture. The titration endpoint wasdetermined with an on-line colorimeter. After titration, the livingpolystyrene chains were transferred via nitrogen pressure from the StepI reactor vessel to the Step II reactor vessel to initiate the Step IIcopolymerization reaction of styrene and butadiene at 30° C. After thetime interval specified in Table 6, the remainder of the butadienemonomer was dosed to the Step II reactor at the specified rate. Thepolymerization was allowed to continue at about 50° C. Some timefollowing the end of the programmed diene addition, generally about30–90 minutes, the signal from an in-line colorimeter which detects thepresence of styryllithium chain ends, was observed to increase sharply.This corresponds to the onset of fast styrene polymerization. Followingthe polymerization of the remaining styrene, which occurs in about 10minutes, the polymer anion is either coupled as described below, orcapped by the addition of a small quantity (1–2 kg.) of butadiene. Asexpected, following the addition of the butadiene, the signal from thecolorimeter decreases dramatically, indicative of the conversion of thechain ends to polybutadienyllithium. This completed the addition of astyrene-butadiene randomized midblock segment to the Step I polystyreneblock. This segment becomes richer in styrene as you proceed away fromthe Step I block, until reaching the short terminal butadiene block.

Coupling with tetraethoxy silane produced the final product. About 0.4to 0.5 moles of the silane were added per mole of polymer anion. Underthese conditions, the predominant coupled species is the linear product,although about 10% –30% of the 3-arm radial polymer is also formed.Coupling efficiency defined as the ratio of coupled species to coupledspecies plus diblock as determined from GPC area, was generally improvedby capping with butadiene. Coupling efficiencies in excess of 90% wereobtained in these examples. Adding an appropriate amount of high-grademethanol to the final reactor solution terminated any living polymerchains. If a short styrene block is formed at the end of thecopolymerization due to tapering, this process guarantees that it willbe located in the central region of the midblock segment. Table 7 showsthe various unsaturated block copolymers prepared in this example.

High midblock styrene/high vinyl polymers can also be prepared by thisgeneral procedure, as illustrated by Polymer #21 in Table 7, which wasprepared by essentially the same process as described above except thediethyl ether concentration was increased to 6% wt. and the rate ofbutadiene addition was increased to reflect the faster reaction rate inthe presence of higher ether levels. In order to insure an adequateexcess of butadiene, the butadiene was added at a rate of about 0.24kg/min for the first few minutes, and the rate was decreased. Theaverage feed rate was about 0.2 kg/min.

Tables 7 and 1a list the various analytical results for the unsaturatedpolymers (unsaturated polymers are polymers 16 to 23). Block I MW is themolecular weight of the first A or polystyrene block in units of 1000,Block II MW is the cumulative molecular weight of the B or controlleddistribution block in units of 1000 and Block III MW is the molecularweight of the final A or polystyrene block in units of 1000. RegardingStep II MW, the first number is the 1,3-butadiene portion and the secondnumber is the styrene portion. For example, in Polymer #16 the B blockhas a molecular weight of 85,000 butadiene and 31,000 styrene, for atotal of 116,000. The weight percent styrene in the mid-block is about26%. The 1,2-vinyl configuration is given, along with the percentstyrene in the entire polymer and in the mid block. For example, forPolymer #16, the entire polymer has about 42 weight percent styrene andthe mid-block has about 26 weight percent styrene (“Calc. Mid PSC” inTable 1a). Coupling efficiency (or CE) is given for each polymer. Thestyrene blockiness for each polymer is calculated and shown in Table 1a(“Calc. Mid Blocky”). Finally the melt flow rate is given for some ofthe polymers.

Illustrative Embodiment #IV

In this example one controlled distribution block copolymer (Polymer#17) was compared against a commercial sample of Styroflex® BX6105, anunsaturated SBS block copolymer from BASF, which has a randomstyrene/butadiene mid-block. Polymer #17 is made with a controlleddistribution styrene/butadiene mid-block according to the presentinvention. Both have similar overall styrene contents as shown in Table8. As shown in Table 8, Polymer #17 has a much improved melt flowmeasured under 200° C./5 kg conditions. Hardness and haze were measuredon injection molded plaques with melt temperatures/injection pressuresof 204° C./1000 psi and 190° C./800 psi for Styroflex and Polymer #17,respectively. Polymer #17 has a lower shore A hardness by approximately20 points and 57% lower haze than Styroflex. Mechanical properties weremeasured on compression-molded plaques pressed at 175° C. and 1250 psi.Even though the tensile strengths are nearly identical, Polymer #17 hasa higher elongation at break. Polymer #17 is also more compliant thanStyroflex as indicated by the consistently lower moduli between 25% and500%. Under a cyclic loading condition, Polymer #17 is more elastic asit recovers twice as much energy with half the permanent set ofStyroflex.

FIG. 5 demonstrates the benefit of the elastomers of the currentinvention. An elastomer is generally characterized by a low initialforce at low deformations, for example below 25% elongation, as opposedto a plastic material which has a much higher initial force. Thecontrolled distribution polymer #17 clearly exhibits much lower force atlow elongations compared to Styroflex, a polymer typical of the currentart of randomized midblock polymers with a similar total styrenecontent. The stiffness at low elongations is typically characterized bythe tensile modulus, or Young's modulus, which is the slope of thestress strain curve at infinitesimal elongation. For example the Young'smodulus of polymer #17 is only 1,400 psi (10 MPa) while for Styroflex itis 5,000 psi (35 MPa). The rubber modulus, or slope between 100 and 300%elongation for polymer#17 is slightly higher, 94 psi (0.65MPa), than forStyroflex, 90 psi (0.62 MPA). Thus the controlled distribution polymerretains the stiff stretch at high elongations and high tensile strengthof a random polymer but with the added benefit of much more elasticbehavior at low elongations. See Table 10, which also displays the glasstransition temperature (Tg) for the B mid-blocks of various polymers.For Polymers 19* and 20* the Tg were taken after hydrogenation.

Illustrative Embodiment #V

In this example two different controlled distribution block copolymers(#15 and #15FG) were compared with KRATON FG-1901 in blends with Nylon6,6 (Zytel 101) at 15 and 20% by weight in a twin screw extruder.Polymer #15FG was prepared by maleating Polymer #15 to a level of 1.7%weight bound maleic anhydride in a Berstorff twin screw extruder. KRATONFG 1901 is an S-EB—S block copolymer that was maleated to a similarlevel of 1.7% weight. The blends were injection molded and the impactstrength was measured using an Izod impact tester. Samples were takenboth from the blind end of the mold and the gate end of the mold tominimize molding effects.

As shown in Table 9, the addition of maleic anhydride dramaticallyimproves the ability of Polymer #15FG to toughen Nylon 6,6. The greatertoughness presented by the maleated Polymer #15FG might allow lessmodifier to be used to achieve the same toughness compared to availablematerials.

TABLE 1 Controlled Distribution Polymers Polymer Step I Step II Step III1,2-BD PSC Number MW(k) MW(k) MW(k) (%) (%) 1 10.5 106.3 118.6 34.529.75 2 10.5 98.6 110.8 38 29.53 3 9.2 90.6 99.9 35.8 40.12 4 9.7 92.3102.8 35.3 48.3 5 13.9 140.8 158.2 35 50.15 6 10.6 101.4 112.6 36.2 40 710.3 99.3 111.9 37.1 40.31 8 8.2 91.2 98.9 37 37 9 32 162 194.8 34.358.1 10 29.4 159.4 189.2 33.6 65.8 11 24 120.9 145.8 33.6 58.9 12 30.3164.3 196.8 35.4 48.2 13 29.9 163.3 195.9 34.5 58.2 14 8.4 88.5 95.836.1 38.3 15 9 86.8 95.5 35.9 39.3 24 29 159 188 35 58 25 9.5 89.5 99 3639 26 7.3 43.1 50.4 36.7 47 27 7.5 70.1 77.4 36.1 40 28 7.8 39 — 36 39where “MW(k)” = true molecular weight in thousands, “1,2-BD, %” is thevinyl content of the butadiene part of the polymer, and “PSC (%)” = wt %of styrene in the final polymer. Molecular weights are cumulative forthe segments (Step II MW = segment MW for Step I and Step II; Step IIIMW is the final MW for the three block copolymers.

TABLE 1a NMR Results for Polymers at the end of Step II Polymer Expt.NMR Expt. NMR Calc. Mid Calc. Mid Number PSC Blocky PSC Blocky 1 22.2 5013.7 10 2 22.2 51 12.9 6 3 33.5 34 26.0 5 4 44.5 27 38.0 4 5 44.7 2938.6 9 6 33.5 33 25.7 3 7 33.5 34 25.8 4 8 32.1 30 25.4 3 9 49.9 43 37.66 10 59.0 34 49.7 4 11 50.4 40 38.1 1 12 38.8 48 25.0 1 13 50.0 39 38.84 14 32.3 30 25.2 1 15 33.4 33 25.7 3 16 42.3 56 26.9 12 17 61.8 45 49.911 18 40.0 59 26.0 22 19 75.4 56 65.7 30 20 38.7 57 23.8 13 21 76.9 5567.1 27 22 74.3 59 63.4 32 23 64.5 57 53.8 33 24 50.7 42 39.7 9 25 33.331 25.7 0 26 38.5 46 26.0 4 27 33.5 34 25.5 3 28 39.4 56 25.4 16

TABLE 2 Conditions for Polymerization of S/B Mid Block CopolymersPolymer # 1 2 3 4 5 6 7 8 Step I Charge Cyclohexane kg 40 40 40 40 59.860 60.4 40.8 Charge Styrene kg 10.04 10 10.2 10.1 15.05 15.1 15.1 10.2sBuLi Titration (12 wt %) ml 20 20 20 55 10 5 20 10 Excess sBuLi (12 wt%) ml 755 755 800 754 745 1065 1062 875 Start Temperature Deg C. 30 3030 30 30 30 30 30 Final Temperature Deg C. 55 50 55 55 55 55 55 55 StepII Charge Cyclohexane kg 170 165 165 200 198 283.4 281 202.7 ChargeStyrene kg 5.05 5 10.02 18.1 18.1 17.12 17.12 11.98 Charge Butadiene kg17.5 17.23 15.5 15.05 15.1 25.6 25.5 18 Charge Diethyl Ether kg 15 15.115.1 18.3 18 25.7 25.6 18.2 sBuLi Titration (12 wt %) ml 30 25 20 55 50130 100 70 Transfer Step I Cement kg 25.1 25.5 25.2 30.8 30.5 42.3 42.925.6 Step I Cement Transfer Rate kg/min n/a n/a n/a n/a n/a n/a n/a n/aStart Butadiene Program @ min 10 10 10 10 10 10 10 10 Program Butadienekg 17.5 17.77 14.5 15.02 15 25.5 25.1 17.8 Butadiene Program Rate kg/min0.29 0.5 0.5 0.5 0.5 0.5 0.5 0.5 Start Temperature Deg C. 30 30 30 30 3030 30 30 Final Temperature Deg C. 55 55 55 55 55 55 55 55 Step IIIProgram Styrene kg 5 5 4.9 5.9 5.8 8.5 8.4 4.2 Styrene Program Ratekg/min n/a n/a n/a n/a n/a n/a n/a n/a MeOH Termination (100 wt %) ml20.2 21 20.3 25 16 35 35 20 Start Temperature Deg C. 55 55 55 55 55 5555 55 Final Temperature Deg C. 57 57 55 55 55 55 55 55 Finished BatchTotal Polymer kg 50 50 50 60 60 85 85 60 Total Cement kg 250 250 250 300300 425 425 300 Solids wt % 20 20 20 20 20 20 20 20

TABLE 3 Polymer Architecture for A1-B-A2 Polymers Block Size (×10³)Polymer A1 B A2 1 10.5 95.8 12.3 2 10.5 88.1 12.2 3 9.2 81.4 9.3 4 9.782.6 10.5 5 13.9 126.9 17.4 6 10.6 90.8 11.2 7 10.3 89.0 12.6 8 8.2 62.37.7 9 32 81.6 32.8 10 29.4 64.7 29.8 11 24 59.9 24.9 12 30.3 102 32.5 1329.9 81.9 32.6 14 8.4 59.1 7.3 15 9 58 8.7 24 29 130 29 25 9.5 80 9.5 267.3 35.8 7.3 27 7.5 62.6 7.5 28 7.8 31.5 —

TABLE 4 Polymer Architecture for A1-B-A2 Polymers Vinyl 1,2 Percentcontent of Styrene in Block Size (×1000) Butadiene B mid block PolymerA1 B A2 (%) (%) 2 10.5 88.1 12.2 38 12.9 3 9.2 81.4 9.3 35.8 26 C-1* 1080 10 68 0 C-2* 10 80 10 38 0 C-3* 10 80 10 52.5 22.9 *actual blocksizes were not measured after synthesis for these 3 polymers, and onlytarget block mol weights are given.

TABLE 5 Tensile Properties Polymer C-1 C-2 2 3 C-3 Stress (psi) at 50%90.5 154.5 170.5 200 196 Stress (psi) at 100% 127.5 203 231 273.5 232Stress (psi) at 200% 173 278 312 401.5 308 Stress (psi) at 300% 222.5383.5 437 606.5 401 Stress (psi) at 500% 367 778.5 908 1304 775 Stressat Break (psi) Max. Stress (psi) 3981.5 4785.5 4575.5 4723.5 4750 Stressat Break (%) Ultimate 1396.5 941.5 871.5 756 1070 Elongation (%) Young'sModulus 2.3 4.4 4.7 5.8 7.7 (MPa) Rubber Modulus 0.32 0.45 0.54 0.670.37 (MPa)

TABLE 6 Conditions for Polymerizations of Low Vinyl S/Bd Mid BlockCopolymers. Polymer # 16 17 18 19 20 22 Step I Charge Cyclohexane kg 106104 96 102 60 100 Charge Styrene kg 26 26.1 24 25 15 25.5 Excess sBuLi(12 wt %) ml 1160 1160 1470 860 900 880 Start Temperature Deg C. 30 3030 30 30 30 Final Temperature Deg C. 55 50 55 55 55 55 Step II ChargeCyclohexane kg 278 273 252 193 193 194 Charge Styrene kg 16.9 32.2 16.131.1 12 31.2 Charge Butadiene kg 16.9 10.7 16 1.8 12 1.7 DistributionAgent DEE DEE nBE DEE ODMB ODMB Charge Dist. Agent g 2100 2300 4000 170010.5 12.25 Dist. Agent Concentration % Wt. 0.5 0.5 1.0 0.5 0.0035 0.0035Transfer Step I Cement kg 103.5 112.5 80.4 110.4 60 107.5 StartButadiene Program @ min 10 1 1 1 1 1 Program Butadiene kg 33.7 21.3 3214.6 22 14.6 Butadiene Program Rate kg/min 0.37 0.25 0.54 0.24 0.32 0.2Charge Butadiene Cap kg None None None 0.8 1.8 0.8 Start Temperature DegC. 30 30 30 30 30 30 Final Temperature Deg C. 50 50 50 50 50 50 Step IIICharge TEOS g 131.2 131.2 139 97.3 93.7 97.3 Finished Batch TotalPolymer kg 88 87 80 70 60 70 Total Cement kg 451 452 400 354 300 362Solids wt % 19 19 20 20 20 19

TABLE 7 Analytical Results for Unsaturated S/Bd Mid-Block Polymers MFRPolymer Block I Block II Block Distribution 1,2-BD PSC CE (200 C/5 kg)No. MW MW III MW Agent (%) (%) (%) (g/10 min) 16 15.5 85/31 15.5 DEE23.5 42 >90 0.6 17 15.6 50/50 15.6 DEE 24.6 63 >90 17.6 18 11.7 75/2511.7 nBE 22.8 40 70 10.8 19 21 38/69 21 DEE 24.3 76 95 11.7 20 12.578/25 12.5 ODMB 23.7 38.8 92 21 21.2 36/65 21.2 DEE 32.6 76 95 22 20.130/65 20.1 ODMB 30 74 94 23 14.8 49/49 14.8 ODMB 25 64.5 90

TABLE 8 Styroflex Polymer #17 BX6105 PSC (%) 63 66 MFR (g/10 min) 17.710.5 Shore A Hardness 62 84 (10s) Haze (%) 21.8 51.3 Tensile TS (psi)4298 4338 Elongation (%) 950 734  25% Modulus (psi) 152 429  50% Modulus(psi) 203 465 100% Modulus (psi) 255 524 200% Modulus (psi) 366 760 300%Modulus (psi) 517 1122 500% Modulus (psi) 917 2125 150% HysteresisRecovered Energy (%) 59.1 30.7 Permanent Set (%) 18.9 38.9

TABLE 9 Formulation (% weight) 9-1 9-2 9-3 9-4 9-5 Polymer # 15 20Polymer 15 20 #15FG KRATON FG 15 20 1901 polymer Nylon 6,6 80 85 80 8580 Notched Izod Impact Test (foot pounds per inch) Gate end 2.05 20.725.1 13.2 21.2 Blind end 2.08 23.6 25.9 13.5 23.1

TABLE 10 Young's Rubber Tg of Modulus Modulus Mid- Polymer (MPa) (MPa)Block  2 4.7 0.54 −31.3  3 5.8 0.67 −22.7  5 −12.6 C-1 2.3 0.32 −31.8C-2 4.4 0.45 −37.4 C-3 7.7 0.37 17 10 0.65 +4.6 Styroflex 35 0.62 19 +2619* +11.5 20* +20.3

1. A process for preparing sulfonated hydrogenated block copolymerscomprising reacting a block copolymer with a sulfonation reagent thatselectively sulfonates the alkenyl arene blocks wherein the hydrogenatedblock copolymer has the general configuration A-B, A-B-A, (A-B)_(n),(A-B-A)_(n), (A-B-A)_(n)X, (A-B)_(n)X or mixtures thereof, where n is aninteger from 2 to about 30, and X is a coupling agent residue andwherein: a. prior to hydrogenation each A block is a mono alkenyl arenepolymer block and each B block is a controlled distribution copolymerblock of at least one conjugated diene and at least one mono alkenylarene; b. subsequent to hydrogenation about 0–10% of the arene doublebonds have been reduced, and at least about 90% of the conjugated dienedouble bonds have been reduced; c. each A block having a number averagemolecular weight between about 3,000 and about 60,000 and each B blockhaving a number average molecular weight between about 30,000 and300,000; d. each B block comprises terminal regions adjacent to the Ablock that are rich in conjugated diene units and one or more regionsnot adjacent to the A block that are rich in mono alkenyl arene units;e. the total amount of mono alkenyl arene in the hydrogenated blockcopolymer is about 20 percent weight to about 80 percent weight; and f.the weight percent of mono alkenyl arene in each B block is betweenabout 10 percent and about 75 percent, g. wherein the styrene blockinessindex of the block B is less than about 40 percent.
 2. The process ofclaim 1 wherein the sulfonation reagent is an acyl sulfate.
 3. Theprocess of claim 2 wherein the acyl sulfate is acetyl sulfate.
 4. Theprocess of claim 3 additionally comprising reacting the sulfonated blockcopolymer with an ionizable metal compound to obtain a metal salt. 5.The process of claim 4 wherein the ionizable metal compound is a Zn²⁺compound.
 6. The process of claim 5 wherein the Zn²⁺ compound is a zincacetate.
 7. The process of claim 1 wherein said mono alkenyl arene isstyrene and said conjugated diene is selected from the group consistingof isoprene and butadiene.
 8. The process of claim 1 wherein saidconjugated diene is butadiene, and wherein about 20 to about 80 molpercent of the condensed butadiene units in block B have1,2-configuration prior to hydrogenation.
 9. The process of claim 1wherein the weight percentage of styrene in the B block is between about10 percent and about 40 percent, and the styrene blookiness index of theB block is less than about 10 percent, said styrene blockiness indexbeing the proportion of styrene units in the block B having two styreneneighbors on the polymer chain.
 10. The process of claim 1 whereinbefore functionaliziation said A block has a glass transitiontemperature of plus 80° C. to plus 110° C. and said B block has a glasstransition temperature of at least above about minus 60° C.
 11. Theprocess of claim 10 wherein before functionalization said B block has aglass transition temperature of between minus 40° C. and plus 30° C. 12.The process of claim 4 wherein the ionizable metal compound comprisesNa⁺, K⁺, Li⁺, Cs⁺, Ag⁺, Hg⁺, Cu⁺, Mg²⁺, Ca²⁺, Sr²⁺, Ba²⁺, Cu²⁺, Cd²⁺,Hg²⁺, Sn²⁺, Pb²⁺, Fe²⁺, Co²⁺, Ni²⁺, Zn²⁺, Al³⁺, Sc³⁺, Fe³⁺, La³⁺ or Y³⁺.13. The process of claim 4 wherein the ionizable metal compoundcomprises a hydroxide, an oxide, an alcoholate, a carboxylate, aformate, an acetate, a methoxide, an ethoxide, a nitrate, a carbonate ora bicarbonate.
 14. The process of claim 1 wherein the styrene blockinessindex of the block B is less than about 10 percent.